I discovered a new bug in mkgmap - see below copy from cmd.exe:
I think this is related to the changes of the bbox or arc length...

Extracting  norway.osm

cache=
description=
geonames-file=cities15000
legacy-mode=false
mapid=64010000
max-areas=128
max-nodes=1300000
mixed=false
overlap=2000
resolution=13
split-file=
write-kml=testkml
Time started: Sun Nov 08 23:33:14 CET 2009
Map is being split for resolution 13:
 - area boundaries are aligned to 0x800 map units
 - areas are multiples of 0x1000 map units wide and high
The input osm file(s) will be re-parsed during the split (slower) because no --cache parameter was specified
Processing norway.osm
2.500.000 nodes processed...
A total of 3.389.190 nodes, 0 ways and 0 relations were processed in 1 file
Min node ID = 110
Max node ID = 559167509
Time: Sun Nov 08 23:33:27 CET 2009
Exact map coverage is (57.715086936950684,4.018828868865967) to (71.18604183197021,31.168577671051025)
Rounded map coverage is (57.7001953125,3.9990234375) to (71.2353515625,31.2451171875)
Splitting nodes into areas containing a maximum of 1.300.000 nodes each...
4 areas:
Area 64010000 covers (0x290800,0x36800) to (0x2af800,0x72800) NO-Bergen
Area 64010001 covers (0x2af800,0x2d800) to (0x2e1800,0x72800) NO-Alesund
Area 64010002 covers (0x299800,0x72800) to (0x2ce800,0x92800) NO-Oslo
Area 64010003 covers (0x2ce800,0x72800) to (0x32a800,0x163800) NO-Trondheim
Writing KML file to testkml
Writing out split osm files Sun Nov 08 23:33:27 CET 2009
Processing 4 areas in a single pass
Starting pass 1 of 1, processing 4 areas (64010000 to 64010003)
Processing norway.osm
2.500.000 nodes processed...
Writing ways Sun Nov 08 23:33:57 CET 2009
Writing relations Sun Nov 08 23:34:05 CET 2009
Wrote 3.389.190 nodes, 194.053 ways, 678 relations
Time finished: Sun Nov 08 23:34:05 CET 2009
Total time taken: 51s
23:34:05
SCHWERWIEGEND (RoadNetwork): Road null (OSM id 35563670) contains zero length arc
SCHWERWIEGEND (RoadNetwork):   http://www.openstreetmap.org/?lat=59.75500&lon=8.14164&zoom=17
java.lang.AssertionError: deltaLong = -37306
        at uk.me.parabola.imgfmt.app.trergn.MapObject.setDeltaLong(MapObject.java:136)
        at uk.me.parabola.imgfmt.app.trergn.MapObject.setLongitude(MapObject.java:125)
        at uk.me.parabola.imgfmt.app.trergn.LinePreparer.calcLatLong(LinePreparer.java:176)
        at uk.me.parabola.imgfmt.app.trergn.LinePreparer.<init>(LinePreparer.java:62)
        at uk.me.parabola.imgfmt.app.trergn.Polyline.write(Polyline.java:165)
        at uk.me.parabola.imgfmt.app.trergn.RGNFile.addMapObject(RGNFile.java:130)
        at uk.me.parabola.imgfmt.app.map.Map.addMapObject(Map.java:242)
        at uk.me.parabola.mkgmap.build.MapBuilder$LineAddFilter.doFilter(MapBuilder.java:1002)
        at uk.me.parabola.mkgmap.build.LayerFilterChain.doFilter(LayerFilterChain.java:57)
        at uk.me.parabola.mkgmap.filters.RemoveEmpty.doFilter(RemoveEmpty.java:61)
        at uk.me.parabola.mkgmap.build.LayerFilterChain.doFilter(LayerFilterChain.java:57)
        at uk.me.parabola.mkgmap.filters.LineSplitterFilter.doFilter(LineSplitterFilter.java:60)
        at uk.me.parabola.mkgmap.build.LayerFilterChain.doFilter(LayerFilterChain.java:57)
        at uk.me.parabola.mkgmap.build.LayerFilterChain.startFilter(LayerFilterChain.java:75)
        at uk.me.parabola.mkgmap.build.MapBuilder.processLines(MapBuilder.java:862)
        at uk.me.parabola.mkgmap.build.MapBuilder.makeSubdivision(MapBuilder.java:643)
        at uk.me.parabola.mkgmap.build.MapBuilder.makeMapAreas(MapBuilder.java:578)
        at uk.me.parabola.mkgmap.build.MapBuilder.makeMap(MapBuilder.java:187)
        at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:96)
        at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:61)
        at uk.me.parabola.mkgmap.main.Main$1.call(Main.java:190)
        at uk.me.parabola.mkgmap.main.Main$1.call(Main.java:188)
        at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Exiting - if you want to carry on regardless, use the --keep-going option
23:35:23